The present invention relates to novel 3, 15 substituted estrone derivatives which represent inhibitory compounds of the 17β-hydroxysteroid dehydrogenase type I (17β-HSD1) enzyme, to their salts, to pharmaceutical preparations containing these compounds and to processes for the preparation of these compounds. Furthermore, the invention concerns the therapeutic use of said novel 3, 15 substituted estrone derivatives, particularly their use in the treatment or prevention of steroid hormone dependent diseases or disorders, such as steroid hormone dependent diseases or disorders requiring the inhibition of the 17β-HSD1 enzyme and/or requiring the lowering of the endogenous 17β-estradiol concentration. In addition, the present invention relates to the general use of selective 17β-HSD1 inhibitors which possess in addition no or only pure antagonistic binding affinities to the estrogen receptor for the treatment and prevention of benign gynecological disorders, in particular endometriosis.
The publications and other materials used herein to illuminate the background of the invention, and in particular, cases to provide additional details respecting the practice, are incorporated by reference.
Mammalian 17β-hydroxysteroid dehydrogenases (17β-HSDs) are NAD(H) or NADP(H) dependent enzymes which catalyse—besides other reactions—the final steps in male and female sex hormone biosynthesis. These enzymes convert inactive 17-keto-steroids into their active 17β-hydroxy-forms or catalyse the oxidation of the 17β-hydroxy-forms into the 17-keto-steroids. Because both estrogens and androgens have the highest affinity for their receptors in the 17β-hydroxy form, 17β-HSD enzymes play an essential role in the tissue-selective regulation of the activity of sex steroid hormones.
At present, 10 human members of the 17β-HSD enzyme family have been described (types 1-5, 7, 8, 10-12). The human 17β-HSD family members share less than 30% similarity in their primary structure. The 17β-HSDs are expressed in distinct, though in some cases, overlapping patterns. The different types of 17β-HSDs also differ in their substrate and cofactor specificities. In intact cells in culture, the 17β-HSDs catalyse the reaction in a unidirectional way: types 1, 3, 5 and 7 use NADP(H) as a cofactor and catalyse the reductive reaction (activation), while types 2, 4, 8 and 10 catalyse the oxidative reaction (inactivation) using NAD(H) as a cofactor [see e.g. Labrie et al. (2000) Trends Endocrinol Metab, 11:421-7, and Adamski & Jakob (2001) Mol Cell Endocrinol, 171:1-4].
Due to their essential role in the tissue-selective regulation of the activity of sex steroid hormones 17β-HSDs can be involved in the occurrence and development of estrogen-sensitive pathologies (f. ex. breast, ovarian, and endometrium cancers etc.) and androgen-sensitive pathologies (f. ex. prostate cancer, benign prostatic hyperplasia, acne, hirsutism, etc). Furthermore, many types of 17β-HSD have been shown to be involved in the pathogenesis of particular human disorders. For example, the 17β-HSD3 is known to be involved in the development of pseudohermaphroditism, the 17β-HSD8 plays a role in polycystic kidney disease and the 17β-HSD4 is related to the occurrence of bifunctional enzyme deficiency. Therefore treatment of sex steroid-sensitive diseases by administration of specific inhibitors of the 17β-HSDs enzymes have been suggested, optionally in combination with potent and specific anti-estrogens and anti-androgens [Labrie F et al. (1997) Steroids, 62:148-58].
Due to the fact that each type of 17β-HSD has a selective substrate affinity, directional (reductive or oxidative) activity in intact cells, and a particular tissue distribution, the selectivity of drug action could be achieved by targeting a particular 17β-HSD isozyme. By individual modulation of the particular 17β-HSDs it is possible to influence or even control the local and paracrine concentration of estrogens and androgens in different target tissues.
The best characterized member of the 17β-HSD family is the 17β-HSD1 [EC 1.1.1.62]. This enzyme could be crystallized in different states of functionality (e.g. with and without ligand and/or co-factor). In vitro, the 17β-HSD1 enzyme catalyses the reduction and the oxidation between estrone (E1) and estradiol (E2). However, under physiological in vivo conditions the enzyme only catalyses the reductive reaction from the estrone (E1) to the estradiol (E2). The 17β-HSD1 was found to be expressed in a variety of hormone-dependent tissues, e.g. placenta, mammary gland tissue or uterus and endometrium tissue, respectively. Estradiol itself is, especially in comparison to the significantly less active estrone, a very potent hormone, which regulates the expression of a variety of genes by binding to the nuclear estrogen receptor and plays an essential role in the proliferation and differentiation of the target cell. Physiological as well as pathological cell proliferations can be estradiol dependent. Especially many breast cancer cells are stimulated by a locally raised estradiol concentration. Furthermore, the occurrence or course of benign pathologies such as endometriosis, uterine leiomyomas (fibroids or myomas), adenomyosis, menorrhagia, metrorrhagia and dysmenorrhoea is dependent from the existence of significantly high estradiol levels.
Endometriosis is a well-known gynecological disorder that affects 10 to 15% of women in the reproductive age. It is a benign disease defined as the presence of viable endometrial gland and stroma cells outside the uterine cavity. It is most frequently found in the pelvic area. In women developing endometriosis, the endometrial cells entering the peritoneal cavity by retrograde menstruation (the most likely mechanism) have the capacity to adhere to and invade the peritoneal lining, and are then able to implant and grow. The implants respond to steroid hormones of the menstrual cycle in a similar way as the endometrium in the uterus. The infiltrating lesions and the blood from these lesions which are unable to leave the body cause inflammation of the surrounding tissue. The most common symptoms of endometriosis are dysmenorrhoea, dyspareunia and (chronic) abdominal pain. The occurrence of these symptoms is not related to the extent of the lesions. Some women with severe endometriosis are asymptomatic, while women with mild endometriosis may have severe pain. Up to now, no reliable non-invasive test is available to diagnose endometriosis. Laparoscopy has to be performed to diagnose the disease. Endometriosis is classified according to the 4 stages set up by the American Fertility Society (AFS). Stage I corresponds to minimal disease while stage IV is severe, depending on the location and the extent of the endometriosis. Endometriosis is found in up to 50% of the women with infertility. However, currently no causal relation has been proven between mild endometriosis and infertility. Moderate to severe endometriosis can cause tubal damage and adhesions leading to infertility. The aims of treatment of endometriosis are pain relief, resolution of the endometriotic tissue and restoration of fertility (if desired). The two common treatments are surgery or anti-inflammatory and/or hormonal therapy or a combination thereof.
Uterine leiomyomas (fibroids or myomas), benign clonal tumours, arise from smooth muscle cells of the human uterus. They are clinically apparent in up to 25% of women and are the single, most common indication for hysterectomy. They cause significant morbidity, including prolonged and heavy menstrual bleeding, pelvic pressure and pain, urinary problems, and, in rare cases, reproductive dysfunction. The pathophysiology of myomas is not well understood. Myomas are found submucosally (beneath the endometrium), intramurally (within the myometrium) and subserosally (projecting out of the serosal compartment of the uterus), but mostly are mixed forms of these 3 different types. The presence of estrogen receptors in leiomyoma cells has been studied by Tamaya et al. [Tamaya et al. (1985) Acta Obstet Gynecol Scand. 64:307-9]. They have shown that the ratios of estrogen receptor compared to progesterone and androgen receptor levels were higher in leiomyomas than in the corresponding normal myometrium. Surgery has long been the main treatment for myomas. Furthermore, medical therapies that have been proposed to treat myomas include administration of a variety of steroids such as the androgenic steroids danazol or gestrinone, GnRH agonists and progestogens, whereby the administration is often associated a variety of serious side-effects.
Everything that has been said above in relation to the treatment of uterine leiomyomas and endometriosis equally applies to other benign gynecological disorders, notably adenomyosis, functional menorrhagia and metrorrhagia. These benign gynecological disorders are all estrogen sensitive and are treated in a comparable way as described herein before in relation to uterine leiomyomas and endometriosis. The available pharmaceutical treatments, however, suffer from the same major drawbacks, i.e. they have to be discontinued once the side-effects become more serious than the symptoms to be treated and symptoms reappear after discontinuation of the therapy.
Since the aforementioned malign and benign pathologies are all 17β-estradiol dependent, a reduction of the endogenous 17β-estradiol concentration in the respective tissue will result in an impaired or reduced proliferation of 17β-estradiol cells in said tissues. Therefore, it may be concluded that selective inhibitors of the 17β-HSD1 enzyme are well suited for their use to impair endogenous productions of estrogens, in particular of 17β-estradiol, in myomas, endometriotic, adenomyotic and endometrial tissue. The application of a compound acting as selective inhibitor on the 17β-HSD1 which preferentially catalyses the reductive reaction will result in a lowered intracellular estradiol-concentration since the reductive conversion of the estrone into the active estradiol is reduced or suppressed. Therefore, reversible or even irreversible inhibitors of the 17β-HSD1 may play a significant role in the prophylaxis and/or treatment of steroid-hormone, in particular 17β-estradiol, dependent disorders or diseases. Furthermore, the reversible or even irreversible inhibitors of the 17β-HSD1 should have no or only pure antagonistic binding activities to the estradiol receptor, in particular to the estrogen receptor a subtype, since agonistic binding of the estrogen receptor would lead to activation and therefore—by regulation of a variety of genes—to the proliferation and differentiation of the target cell. In contrast, antagonists of the estrogen receptor, so called anti-estrogens, bind competitively to the specific receptor protein thus preventing access of endogenous estrogens to their specific binding site.
At present it is described in the literature that several malignant disease as breast cancer, prostate carcinoma, ovarian cancer, uterine cancer, endometrial cancer and endometrial hyperplasia may be treated by the administration of a selective 17β-HSD1 inhibitor. Furthermore, a selective 17β-HSD1 inhibitor may be useful for the prevention of the aforementioned hormone-dependent cancers, especially breast cancer. The international patent application WO 2004/080271 discloses the use of a particular 17β-HSD1 inhibitor, so called compound A, for prevention or treatment of disorders caused by the 17HSD1 enzyme activity, in particular breast cancer. Furthermore, the international patent application WO 03/017973 describes the use of a selective estrogen enzyme modulator (SEEM) in the manufacture of a drug delivery vehicle for use in a method of treating or preventing a benign gynecological disorder in a mammalian female, said benign gynecological disorder being selected from the group consisting of uterine leiomyomas, endometriosis, adenomyosis, functional menorrhagia and metrorrhagia, wherein the method comprises the intravaginal administration of the SEEM to the female suffering from the benign gynecological disorder in a therapeutically effective dosage to prevent or reduce the symptoms of said benign gynecological disorder, said SEEM being selected from the group consisting of aromatase inhibitors, cyclo-oxygenase 2 (COX-2) inhibitors, 17β-HSD1 inhibitors and combinations thereof.
Several reversible or irreversible inhibitors of the 17β-HSD1 enzyme of steroidal and even non-steroidal origin are already known from the literature. The characteristics of these inhibitory molecules, which mainly have a substrate or cofactor-like core structure, have been reported in the literature [reviewed in: Poirier D. (2003) Curr Med Chem. 10:453-77].
For example, Tremblay and Poirier describe an estradiol derivative, 16-[carbamoyl-(bromo-methyl)-alkyl]-estradiol, and tested the same in respect of its inhibition of the estradiol formation catalysed by the enzyme 17β-HSD1 [Tremblay & Poirier (1998) J. Steroid Biochem. Molec. Biol., 66:179-191]. Poirier and colleagues describe a 6β-thiaheptan-butyl-methyl-amide derivative of estradiol as a potent and selective inhibitor of the 17HSD1 enzyme [Poirier et al. (1998) J. Steroid Biochem. Molec. Biol., 64:83-90]. Furthermore, Poirier and colleagues describe new derivatives of 17β-estradiol with N-butyl, N-methyl alkylamide side chains of three different lengths (n=8, 10 or 12) at position 15, which might be potential inhibitors of the 17β-HSD enzyme [Poirier et al. (1991) Tetrahedron, 47(37):7751-7766]. The biological activity of these compounds was only tested with regard to estrogen receptor binding affinity, estrogenic and anti-estrogenic activity [Poirier et al. (1996) Bioorg Med Chem Lett 6(21):2537-2542]. In addition, Pelletier and Poirier describe novel 17β-estradiol derivatives with different bromo-alkyl side chains, which might be potential inhibitors of the 17β-HSD enzyme [Pelletier & Poirier (1996) Bioorg Med Chem, 4(10):1617-1628]. Sam and colleagues describe several estradiol derivatives with a halogenated alkyl side chain in 16α or 17α position of the steroidal D ring which possess 17β-HSD1 inhibiting properties [Sam et al. (1998) Drug Design and Discovery, 15:157-180]. Furthermore, the finding that some anti-estrogens, such as tamoxifen, possess weak 17β-HSD inhibiting properties suggested that it may be possible to develop a potent 17β-HSD1 inhibitor that is also anti-estrogenic [reviewed in: Poirier D. (2003) Curr Med Chem. 10:453-77]. Several of the aforementioned already known compounds also display anti-estrogenic properties (e.g. the 60-thiaheptan-butyl-methyl-amide derivative of estradiol described by Poirier and colleagues [Poirier et al. (1998) J. Steroid Biochem. Molec. Biol., 64:83-90]). None of the aforementioned compounds has been clinically used so far.
International patent application WO 2004/085457 discloses a variety of estron derivatives with different substituents in C3, C6, C16 and/or C17 position as potent 17β-HSD1 inhibitors.
The synthesis of different B-, C- and D-ring substituted estradiol carboxylic esters was described by Labaree et al. [Labaree et al. (2003) J. Med. Chem. 46:1886-1904]. However, these esters were only analyzed with regard to their estrogenic potential. The related international patent application WO 2004/085345 discloses 15α substituted estradiol compounds bearing a —(CH2)m—CO—O—R side chain, wherein R is H, a C1 to C5 alkyl group, optionally substituted with at least one halogen group, such as CH2CH2F, or other group (e.g. CH2CHF2, CH2CF3 or CF3 group); and m is from 0-5. This 15α estradiol esters are described as locally active estrogens without significant systemic action.
Accordingly, there is a need for the development of compounds which are suited for the treatment and/or prevention of steroid hormone dependent diseases or disorders such as breast cancer, endometriosis and uterine leiomyomas by selectively inhibiting the 17β-HSD1 enzyme, while desirably failing to substantially inhibit other members of the 17β-HSD protein family or other catalysts of sex steroid degradation or activation. In particular, it is an aim of the present invention to develop selective inhibitors of the 17β-HSD1 enzyme, whereby in addition the compounds have no or only pure antagonistic binding affinities to the estrogen receptor (both subtypes α and β). Furthermore, there is still a need to provide a new type of therapy regimen for estrogen dependent benign gynecological disorders, particularly for pre- and peri-menopausal females, whereby the therapy should not cause serious side-effects.